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THE EFFECT OF LIGHT ON THE ESR SPECTRA OF HUMIC ACIDS
Author(s) -
SLAWINSKA D.,
SLAWINSKI J.,
SARNA T.
Publication year - 1975
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1975.tb01934.x
Subject(s) - electron paramagnetic resonance , humic acid , oxygen , chemistry , aqueous solution , spectral line , signal (programming language) , relaxation (psychology) , irradiation , photochemistry , amplitude , analytical chemistry (journal) , nuclear magnetic resonance , environmental chemistry , organic chemistry , physics , optics , psychology , social psychology , fertilizer , astronomy , computer science , nuclear physics , programming language
Summary Photo‐induced Electron Spin Resonance signals have been detected in basic aqueous solutions of humic acids from soil and from synthetic and commercial sources. Parameters of these signals under atmospheres of air, O 2 and N 2 were the same as or very similar to those of the already known ‘dark’ stable ESR‐signals of humic acids and melanins. The maximum increase of signal amplitude under the influence of 395–780 nm wavelength irradiation was one order of magnitude. The influence of microwave power on ESR‐signal amplitude was examined under different atmospheres. It has been found that oxygen strongly diminishes the saturability of signals. This indicates that oxygen has an influence upon relaxation properties of paramagnetic centres of humic acid. Photoinduced ESR signal is a newly discovered feature of humic acids, similar to that of melanin and may be expected to affect physico‐chemical processes occurring in soils.